"Use the pass to cross the Pontar" is a quest objective in the sidequest "Thou Shall Not Pass" in The Witcher 3: Wild Hunt
Story
You acquired a pass that will grant you passage through the border.
Use the pass to cross into either Novigrad or Oxenfurt
Quest
NPCs
Walkthrough
Use the pass at one of the following locations:
- Border Post
- Oxenfurt West Gate
Dialog
Redanian Soldier: Oh, it's you... can't let you pass without a... pass.
Geralt: Perfect. Just so happens I have a pass.
Redanian Soldier: What? Lemme see... doesn't seem forged, but you never know... all right, move on.